【作者】 梁文婧；

【导师】 冯晅；

【作者基本信息】 吉林大学 ， 固体地球物理学， 2012， 硕士

【摘要】 探地雷达（Ground Penetrating Radar简称GPR）又称为地质雷达，是一种高效无损的浅层地球物理探测技术，通过发射天线向地下发射高频电磁波，经接收天线接收反射回地面的电磁波，通过电磁波在地下介质中传播时，遇到电性差异的界面发生反射，根据接收到电磁波的波形、振幅强度和时间的变化特征来确定地下结构的一种方法。具有携带方便、易操作、场地适应能力强、抗干扰能力强和探测分辨率高等特点。极化描述了电磁场矢量端点随时间变化所形成的空间轨迹的方向和强度。其在目标体信息的获取、雷达数据处理及解释过程中起着重要作用。它是雷达目标散射信号中重要的信息，在抗有源干扰和杂波干扰、目标信号滤波和增强、目标检测和目标识别(表面粗糙度，对称性，取向)中有着巨大的潜力。随着极化测量技术的日趋完善，极化研究的意义也日趋重要。当前的雷达极化理论技术体系已初步形成，在此基础上，本论文提出将探地雷达与极化技术相结合，构建了全极化探地雷达硬件系统。在测试了新型Vivaldi天线性能的基础上，组建具有一次性获取全极化数据测量能力的天线阵列，此极化天线阵列可压制噪音且实现多次覆盖，并应用此天线阵列系统进行一系列典型目标体极化性能的测试。本论文结合极化理论与探地雷达原理，自主构建全极化步进频率探地雷达（FP-SFGPR）系统。系统主要以矢量网络分析仪（VNA）为中心而设计构建，由矢量网络分析仪、三维直角坐标机器人、计算机控制单元、全极化天线阵列组成。该系统结构的主要设计思想是，完成定位，测量，存储数据自动化，获得高精度和信息量丰富的数据，同时对控制功能进行模块化设计，从而优化操作，使其简便易行，减少误差。操作员通过编写VBA程序实现在计算机上对三维直角坐标机器人的移动，矢量网络分析仪射频信号的发射接收、数据的采集存储等功能的控制。在全极化探地雷达硬件系统中，天线是最为重要的组件之一，其性能直接关系到系统测量精度。因此，本文详细介绍新型Vivaldi天线各项基本性能的测试，如回波损耗，传输函数，驻波比，方向图等，基于新型Vivaldi天线自身具有良好的极化性能，宽频带，极化率高等特点，又将单一方式极化天线组合改进成极化天线阵列，使得在不同的测量情况下能够对目标体完成极化测量任务，更好的补偿或者对相位的分散移动进行抑制。并借鉴勘探地震中的多次覆盖技术，研发多次覆盖极化天线阵列，通过采集共中心点(CMP)数据，经过叠加CMP数据来压制噪音，提高信噪比。在测试了新型Vivaldi天线阵列性能的基础上，利用全极化步进频率探地雷达系统对典型目标体进行了测试，实测目标体的响应结果与全极化探地雷达正演模拟的结果具有较好的一致性，说明该系统可较精确的完成电磁波测量实验，为验证正演模拟的理论结果提供良好的实验平台。通过对地下目标体的探测实验，得出结论，具有多种雷达视角的典型目标体的交叉极化信息显示出一定规律性，通过交叉极化响应和共极化响应信息的综合使用有助于我们对目标的形状、方位等属性进行识别判断，通过交叉极化响应和共极化响应信息的综合使用有助于我们对目标的形状、方位等属性进行识别判断。总之，本论文的主要研究内容在于全极化探地雷达硬件系统的构建及对地下典型目标体的共极化和交叉极化信息进行分析。研究目的是为电磁波研究、天线研究提供基础的实验平台，为验证全极化探地雷达相关理论提供精确地实验依据。更多还原

【Abstract】 Ground-Penetrating Radar (GPR) is an effective shallow geophysical detectiontechnique. It has the advantages of bring convenient, operation simply,anti-interference, site adaptability and high detection resolution.Polarization describes the electromagnetic field vector endpoint as a function oftime formed the direction and amplitude of space locus. It plays an important role inacquisition of target information, radar data processing and interpretation. It is theimportant information of radar scattering signal, it has a great potential inanti-interference and anti-clutter, target signal filtering and enhancement, targetdetection and recognition (surface roughness, symmetry, orientation).Though GPR is used widely, based on the development of radar polarizationtheory and polarization technique in data information processing, in this paper, wehave applied the polarimetric technology in the GPR detection, and developed afull-polarimetric radar acquisition system to improve the capability of radar targetclassification and recognition. Basing on the Vivaldi antenna performance testing,Using this system，we have done some experiments for detecting the polarimetricproperties of typical targets.In this work, based on radar measurement principle and the polarimetric theory,we are trying to import the full polarization technique into the GPR system anddeveloping a full polarimetric GPR acquisition system, which consists of computer,vector network analyzer (VNA), three-dimension rectangular coordinate controldevice, Vivaldi antenna etc. By using VB language, we put the controls of vectorNetwork Analyzer and three-dimensional Cartesian coordinate system in the computer.Implement the entire system automatic operation. With the advantages of this system,we can set the positions of the measuring line and points accurately, realize multipleparameters testing at the same time, storage a variety of data automatically.Antenna is a key component of Radar acquisition system，the merits of theirperformance is directly related to the accuracy of radar acquisition system. Therefore,after the completion of system integration, we used the radar acquisition system totested the performance of Vivaldi antenna, Including return loss, VSWR, pattern,transfer function etc., The results showed that the Vivaldi antenna possesses a widebandwidth, energy radiation focused, better polarimetric balance, a high cross-polarization ratio, and it may use polarization measurements, and can be usedfor polarization measurements. Based on the Vivaldi antenna performance, we haveapplied the full-polarimetric GPR system to test polarimetric properties of typicaltargets. The measured targets consist with the forward models. We have tested co-andcross-polarimetric signal of typical targets, respectively, including polarimetricperformance measurements of different angles. The experiment results show that fullpolarimetric information will help us to identify target attributes such as orientation.So depending on the polarimetric antenna array, we obtain more polarimetricinformation to help us enhance the GPR capability of discrimination and imaging ofsubsurface targets.In short, the main content of this thesis are full-polarimetric GPR acquisitionsystem construction and a high quality object profile was constructed in bothexperiments. Use the effects of polarized information in anti-clutter interference targetrecognition to enhance the sensitivity, stability and object identification andclassification ability of GPR.更多还原